Chelsea have had a second bid for centre-back Alessio Romagnoli worth up to £34m rejected by AC Milan.
After having an initial bid of £30m rejected, Chelsea went back to the Rossoneri with an offer of an initial £30m payment, plus up to a further £4m in incentives, but Milan's directors have told sources in Italy the player is "unsellable".
The following was tweeted from AC Milan's account on Thursday: "#ACMilan has received a significant offer for its player Alessio Romagnoli from @ChelseaFC, but the player is not for sale."
The 21-year-old Romagnoli is seen as one of the brightest prospects in Italian football and joined Milan last summer from Roma in a £21m deal.
Despite his relative lack of experience, he quickly established himself as a pivotal member of Milan's defence and went on to make 34 appearances last season and has been compared to Alessandro Nesta and Thiago Silva from the Italian press.
Chelsea switched their attention to Romagnoli after having a £38m bid rejected by Napoli for Senegal international centre-back Kalidou Koulibaly at the end of July.
Antonio Conte has made strengthening the heart of Chelsea's defence a priority this summer with Kurt Zouma's long-term knee injury leaving him short of options.
After his side won 2-1 at Watford on Saturday, Conte stressed the need for the Blues to land a new defender before the transfer window closes on August 31.
"If you look now at our squad, we have only five defenders - four that started today and an academy player Ola Aina," said Conte.
"Ola is very good - he has great potential - but with any young player you must work to put them in the first team. Sure, he has a good future.
"If one defender is injured or banned, then we are in trouble, but the club and me we know this and we are talking every day to improve the squad."